The Oscar-winning film director Charles Ferguson has cancelled his CNN documentary on Hillary Rodham Clinton after what he described as a private campaign against the film by prominent Democrats.

Ferguson pulled the plug after being met with a wall of silence from more than 100 people who refused to be interviewed.

He said aides to the former Democrat secretary of state under Barack Obama put pressure on CNN and made it clear Clinton would co-operate only "over my dead body".

He also blamed a campaign by Republicans, who said the film would be biased in favour of Clinton. "Neither political party wanted the film made," moaned Ferguson. "After painful reflection, I decided I couldn't make a film of which I would be proud."

Ferguson claimed Clinton's spokesman, Phillipe Reines, had "interrogated" various executives at CNN about the documentary before it was announced by the broadcaster in July.

"When I approached people for interviews, I discovered that nobody, and I mean nobody, was interested in helping me make this film," said Ferguson.

"Not Democrats, not Republicans - and certainly nobody who works with the Clintons, wants access to the Clintons, or dreams of a position in a Hillary Clinton administration.

"Not even journalists who want access, which can easily be taken away. I even sensed potential difficulty in licensing archival footage. After approaching well over 100 people, only two people who had ever dealt with Mrs Clinton would agree to an on-camera interview - and I suspected that even they would back out."

The campaign against the film began almost immediately after it was announced by CNN.

The Republican national committee announced that its members would boycott the network over the Republican presidential primary debates in 2016.

"This did not surprise me. What did surprise me was that, quietly and privately, prominent Democrats made it known both to CNN and to me that they weren't delighted with the film either," said Ferguson.

This article appeared in the South China Morning Post print edition as Director drops Clinton film over political pressure